Miracle Gro 15-30-15??

Thursday night i transplanted my plants into a bigger pot, 3 gallon. and well i had it in a plastic cup so i cut the cup open and transplanted it along with the old soil. the old soil was really dry by that point but since the new soil was in perfect conditions i didnt water, just planted it. well my question is should i water it in the spot where it has the old dry soil? also, i have some miracle gro 15-30-15, should i use this? well i get high everyday, or at least i try to, so i dont remember how old my plants are and i know i posted that they were like 15 days before, but i think i was wrong, they are about 17 days as of now saturday oct. 30. i have 3 plants, two of them have 4 sets of leaves working on their fifth, and the other one i think got shocked the first time i moved it cuz its been growin slower, it has 3 sets working on its fourth. i have two more questions, are purple stems good? bad? and also i read that the leaves only have odd number blades, well i have 2 or 3 leaves with 6 blades. i dunno if any of you have ever seen that, but is that bad? or it okay? sorry to ask so many questions but first time growing and i need to become good, lol. but yeah, all your guys's help would be greatly appreciated.